Refrigeration system for cabinets

ABSTRACT

An improvement in a refrigeration system for cabinets provided with a top cover and with internal peripheral walls made of metallic sheet and around which is seated an evaporating means ( 1 ) connected to the outlet of an expanding device ( 2 ) which is connected to the outlet pf a condenser ( 3 ) and to the suction of a compressor ( 4 ) of the refrigeration system, said evaporating means ( 1 ) comprising at least two tube extensions ( 10 ), each of them being seated around a respective height portion of the internal peripheral walls (P) and having a refrigerant fluid inlet end maintained in fluid communication with a respective expanding device ( 2 ), and a refrigerant fluid outlet end maintained in fluid communication with the compressor ( 4 ).

FIELD OF THE INVENTION

The present invention refers to an improvement introduced in therefrigeration system of cabinets, such as those applied to horizontalfreezers used for cooling or preserving beverages or other products andwhich comprise a cabinet provided with a top cover.

BACKGROUND OF THE INVENTION

There are well known from the art the refrigerated cabinets providedwith a top cover and in which the internal peripheral walls are formedin metallic sheet to operate as a heat exchange enhancing element for anevaporator which is usually defined by a tube seated against theexternal face of said internal peripheral walls, in a downward spiraldevelopment along at least part of the cabinet height.

The upper end of the tube is connected to the expanding element of therefrigeration circuit, the lower end of said tube of the evaporatorbeing maintained in fluid communication with the suction of thecompressor that compresses the refrigerant fluid of the refrigerationsystem.

In the cabinets of the type considered herein, the refrigerant fluidwhich reaches the upper end of the evaporator, coming from the capillarytube, is evaporated as it flows down the tube, exchanging heat with thethermal load mainly defined by the product to be cooled and which isstored inside the cabinet.

Although adequately operating under normal conditions of re-supplyingthe thermal load to be refrigerated, the cabinet refrigeration systemsarranged in the manner described above are deficient when the thermalload is replaced in a high frequency, which usually occurs when thesecabinets are used as a beverage cooler or preserver.

When the refrigeration system of these cabinets is submitted to a highthermal load resulting from a severe loading, the evaporation rate ofthe refrigerant fluid therein becomes very high, making the liquidportion of the refrigerant fluid which reaches the evaporator to berapidly evaporated in the upper part of the internal peripheral walls ofthe cabinet, practically stopping the refrigeration operation from themoment the whole refrigerant fluid is evaporated, passing to the vaporstate.

As the thermal load is refrigerated from top to bottom, the lower regionof the evaporator, which is useless in terms of heat exchange by thefact that it receives only the already vaporized refrigerant fluid, isprogressively reduced, making the evaporator to be also progressivelymore efficient.

The operational deficiency discussed above, resulting from the reductionof the heat exchange useful extension of the evaporator, exactly in themoment of highest requirement (with the higher thermal loading of thecabinet) is undesired, since it results in a slower refrigeration rateof the product stored in the cabinet.

OBJECT OF THE INVENTION

It is an object of the present invention to provide an improvement in arefrigeration system for cabinets of the type discussed above, whichincreases the heat exchange useful extension of the evaporator underhigh thermal load conditions inside the cabinet, without requiringconstructive alterations to be effected in the latter.

SUMMARY OF THE INVENTION

The improvement of the invention is introduced in a refrigeration systemfor a cabinet provided with a top cover and with internal peripheralwalls, made of metallic sheet and around which is seated an evaporatingmeans connected to the outlet of an expanding device (in its turnconnected to a condenser) and to the suction of a compressor of therefrigeration system.

According to the invention, the evaporating means comprises at least twotube extensions, each of them being seated around a respective heightportion of the internal peripheral walls, and having a refrigerant fluidinlet end maintained in fluid communication with a respective expandingdevice and a refrigerant fluid outlet end maintained in fluidcommunication with the compressor.

Besides reducing the time of refrigeration of a high thermal load, as afunction of the reduction of the useless extensions of the evaporator,when operating under determined severe conditions the constructivearrangement described above allows reducing, diametrically, the tubeextensions of the evaporator, without increasing the velocity of therefrigerant fluid inside the evaporator. Reducing the diameter of thecapillary tube leads to a relevant cost reduction of this material.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be described below, with reference to the encloseddrawing, in which:

FIG. 1 is a schematic lateral view of an internal peripheral wall of acabinet associated with a refrigeration system provided with anevaporating means constructed according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The single figure of the enclosed drawing illustrates a lateral view ofan internal peripheral wall P, in metallic sheet, of a parallelepipediccabinet provided with a top cover (not illustrated).

Around the internal peripheral walls P of the cabinet is seated andaffixed an evaporating means 1, which in the illustrated examplecomprises two tube extensions 10, each of them being seated around arespective height portion of the internal peripheral walls P.

It should be understood that three or more evaporating portions might beprovided affixed around the internal peripheral walls P of the cabinet,each evaporator portion being defined by a respective tube extension 10disposed in the same spiral development usually applied to this type ofevaporating means which uses the internal peripheral walls P of thecabinet as heat exchange fins of the tube extensions, each evaporatorportion being connected to an expanding device 2 of refrigerant fluid.

Each tube extension 10 presents a refrigerant fluid inlet end maintainedin fluid communication with the outlet of a respective expanding device2, which in turn is connected to the outlet of a condenser 3 of therefrigeration system, and an outlet end of vaporized refrigerant fluidmaintained in fluid communication with a compressor 4 of saidrefrigeration system.

With the arrangement described above, the evaporating means is replacedby two or more tube-type evaporators, which are arranged in parallel,each covering a portion of the cabinet height, thereby allowing a fasterand more homogeneous cooling of the thermal load which will be placed inthe cabinet.

The parallel arrangement of the evaporators or tube extensions 10 allowsthe diameter of the capillary tube to be reduced, in order to define across-sectional area which is slightly smaller than a portion of thecross-sectional area of the prior art tube required to form theevaporating means with a single continuous tube extension, correspondingto the number of tube extensions 10.

1. An improvement in a refrigeration system for cabinets provided with atop cover and with internal peripheral walls (P), made in metallic sheetand around which is seated an evaporating means (1) connected to theoutlet of an expanding device (2) which is connected to the outlet of acondenser (3) and to the suction of a compressor (4) of therefrigeration system, characterized in that the evaporating means (1)comprises at least two tube extensions (10), each of them being seatedaround a respective height portion of the internal peripheral walls (P)and having a refrigerant fluid inlet end maintained in fluidcommunication with a respective expanding device (2), and a refrigerantfluid outlet end maintained in fluid communication with the compressor(4).
 2. The improvement as set forth in claim 1, characterized in thatthe tube extensions (10) are formed by a tube with a reduced diameter,in order to define a cross-sectional area which is slightly smaller thana portion of the cross-sectional area of the tube required to form theevaporating means with a single continuous tube extension, correspondingto the number of tube extensions (10).